Arduino reads punched cards for cloud computing | Hacker News Reader

Arduino reads punched cards for cloud computing

blog.arduino.cc

33 pointsPaulHoule11 comments

My dad's official designation was Punch Card Operator; he used to bring the used ones back from office. Since they were made of good quality thick paper, the back of the card was great for writing notes, grocery lists; also excellent bookmarks.

A hole at any of those points could represent either a one or zero

That's not quite correct. There were twelve rows: 0-9, 11 and 12. A hole in row 0 was a zero, etc. Holes in 12 + 1 was an 'A', 11 + 1 was 'J', and 0 + 2 was 'S'. Other combinations were for punctuation.

That is just EBCDIC character encoding scheme. Its still ones and zeroes in the end. You can see this in this example card on Wikipeidas article on EBCDIC https://en.wikipedia.org/wiki/EBCDIC#/media/File:Blue-punch-...

Where I work we have some old card decks that are in “column binary” format that occasionally we have to convert to some more modern format.

http://ropercenter.cornell.edu/data-archaeology-uncovering-p...

https://documentation.sas.com/doc/en/lrcon/9.4/p0wq84yjj4qkt...

Punched card/tape readers that work using either electrical contact through the holes or light sensors just as this one are intuitive for me, but I have never seen an explanation of how entirely mechanical readers work Edit: found this: "Paradise Mill How The Jacquard Mechanism Works" https://www.youtube.com/watch?v=x_ijmjx7Xys and "How was it Made? Jacquard weaving": https://www.youtube.com/watch?v=K6NgMNvK52A

While I've never seen a thorough explanation either, it seems intuitive enough to me. A sprung pin will fall through the hole of a punchcard, and will not if there is no hole. The motion of that pin can be amplified through clockwork to drive a greater mechanism. Note particularly the escapement:

https://ciechanow.ski/mechanical-watch/

At least for tape, that must have caused quite a bit of wear

Non-reusable/limited use source code :D

If you do it right, it shouldn't cause significant wear to the punched cards. You'd want to move the cards with the pins up, and then drop the pins (read head) after moving them. Each pin wouldn't need to exert much force on the paper, nor should the pins be dragged in and out of the paper hole. From everything I've read, the card sets were used many times -- at least one mention on the wikipedia article of a set of cards being used over 100 times.

Oh, and wikipedia has a nice figure from, I believe, Jacquard's patent.

https://en.wikipedia.org/wiki/Jacquard_machine#/media/File:T...

Original youtube video from Ivanov: https://www.youtube.com/watch?v=Oke-7lsvFug

Kudos for the low power processing. I can imagine that image based reading would be trivial today, on more powerful hardware...

the low depends on the volatile price of apples. That hand doesn't move for free

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